Infectious Diseases STIS The Chain of Infection Chain

Infectious Diseases STIS

The Chain of Infection Chain of infection: the process by which an infectious agent, or pathogen, passes from one organism to another Pathogen: infectious agent capable of causing disease ◦ They often live in large communities, called reservoirs ◦ Some cannot survive in the environment and require a living host ◦ To cause infection, they must have a portal of exit from the reservoir or host, and a portal of entry into a new host 2

The Chain of Infection • Vector: animal or insect that transmits a pathogen from a reservoir or an infected host to a new host • Breaking the chain of infection at any point can either increase or decrease the risk of infection • Virulence: speed and intensity with which a pathogen is likely to cause an infection • Epidemic: widespread outbreak of a disease that affects many people 3

The Chain of Infection • Vector: animal or insect that transmits a pathogen from a reservoir or an infected host to a new host • Breaking the chain of infection at any point can either increase or decrease the risk of infection • Virulence: speed and intensity with which a pathogen is likely to cause an infection • Epidemic: widespread outbreak of a disease that affects many people 4

Types of Pathogens 5

Bacterial STIs • Chlamydia • Most common bacterial STI; young women at greatest risk • Gonorrhea • Highest rates in young women; Blacks 17 times higher than Whites • Pelvic inflammatory disease • Infection of uterus, fallopian tubes, and/or ovaries • Syphilis • If untreated, can lead to serious complications • Bacterial vaginosis (BV) • Alteration of the normal vaginal flora 6

Viral STIs Human papillomavirus (HPV) ◦ Most common STI in the U. S; more than 40 types Genital herpes ◦ No cure; prevention particularly important Hepatitis ◦ Inflammation of the liver 7

Other STIs Trichomoniasis ◦ Caused by a protozoan; transmitted from person to person by sexual activity Candidiasis ◦ Vaginal yeast infection Pubic lice and scabies ◦ In adults, most often sexually transmitted 8

HIV/AIDS • Cause: HIV virus attacks the helper T cells (CD 4) and macrophages of the immune system • Methods of transmission: • Sexual contact; direct contact involving the exchange of bodily fluids (blood, semen, vaginal secretions) • Sharing of hypodermic needles • Through infected blood products • Perinatal transmission (mother to fetus) 9

HIV/AIDS • Most infected people are asymptomatic or can remain symptom-free for years, even though antibodies have been formed within weeks of infection • Eventually the following symptoms may appear due to opportunistic infections: • • • Rapid weight loss Cough Night sweats Diarrhea Rashes or skin blemishes Memory loss 10

People Living with HIV in 2012 11

HIV Testing • Strongly recommended for anyone who has engaged in or has a partner who has: • • Injected drugs, including steroids Had unprotected sex (vaginal, anal, or oral) Had multiple partners or has exchanged sex for drugs or money Been diagnosed with an STI • Multiple new tests, using oral swabs or urine instead of blood • Home Access HIV-1 Test System (home test kit) 12

Management of HIV/AIDS • Antiretroviral agents: do not cure the infection, but slow the rate of replication and destruction, prolonging life and improving quality of life • Drug cocktails: complicated drug combinations that combat the development of resistant viral strains • Complexity, cost, and risk of side effects increase • New prevention possibilities • Vaccine trials are under way • Microbicide 13

Disproportionate Risk for HIV Infection 14

Sexually Transmitted Diseases STDs can occur in men, women, and children. They are passed from person to person through sexual contact or from mother to child.

Table 18. 2 Sexually Transmitted Diseases

Table 18. 2 (continued) Sexually Transmitted Diseases

Figure 18. 10 Genital warts. (Courtesy of the Centers for Disease Control and Prevention)

Table 18. 2 (continued) Sexually Transmitted Diseases

Table 18. 2 (continued) Sexually Transmitted Diseases

Table 18. 2 (continued) Sexually Transmitted Diseases

Table 18. 2 (continued) Sexually Transmitted Diseases

Table 18. 2 (continued) Sexually Transmitted Diseases